Simple .NET/ASP.NET PDF document editor web control SDK

private void MakeListViewItemForNewEntry(int newItemIndex) { ListViewItem item = new ListViewItem(); item.SubItems.Add(""); entriesListView.Items.Insert(newItemIndex, item); }

barcode font for microsoft excel 2007, barcode excel 2007 add in, create barcode in excel 2016, barcode font for excel download, barcode erstellen excel kostenlos, free barcode generator for excel 2013, free online barcode generator excel, excel barcode font, active barcode in excel 2010, barcode in excel,

Creating an event filter is easier than inheriting a widget class and overriding an event handling class An event filter is a class inheriting QObject that implements the eventFilter(QObject*, QEvent*) method The method makes it possible to intercept events before they reach their destinations The events can then be filtered (let through or stopped) Event filters can be used to implement many special functions, such as mouse gestures and recognizing key sequences They can be used to enhance widgets or to change a widget s behavior without having to subclass the widget Let s try an event filter that removes any numerical key presses from the event queue The class declaration and implementation is shown in Listing 6-16 The interesting part is the eventFilter method, which has two arguments: a pointer to the destination QObject (dest) and a pointer to the QEvent object (event).

This code doesn t bother to provide values for the newly created item, because the binding source immediately follows a new item notification with an item change notification. So by putting code to update the list view item in the change notification handler, shown in Example 22-5, we cover two cases: new items and changes to existing items.

private void UpdateListViewItem(int itemIndex) { ListViewItem item = entriesListView.Items[itemIndex]; ToDoEntry entry = entries[itemIndex]; item.SubItems[0].Text = entry.Title; item.SubItems[1].Text = entry.DueDate.ToShortDateString(); }

Finally, Example 22-6 shows the code for handling deleted items. We ve not added the code to perform deletions yet, but we need this method in place for Example 22-3 to compile.

By checking whether the event is a key press event using type, you know that the event pointer can be cast to a QKeyEvent pointer The QKeyEvent class has the text method that you use to determine whether the key pressed is a number If the key press is from a numerical key, true is returned, indicating that the filter handled the event This stops the event from reaching the destination object For all other events, the value of the base class implementation is returned, which will result in either handling the event by the base class filter or letting it pass through the final destination object Listing 6-16 The event filtering class KeyboardFilter stops key presses for numeric keys.

private void RemoveListViewItem(int deletedItemIndex) { entriesListView.Items.RemoveAt(deletedItemIndex); }

Implementing this using behaviors is easy. Before you begin, however, make sure you have the full stylesheet called intro.css that defines the styles used by these panes. You can find it listed in 4, and it is also available as part of the download with this book. First you need to implement the panes in HTML and assign identities to them. You can see the two panes from the example here: <div id="Description"> <div id="DragHandle"> Drag by clicking on this element </div> <div style="text-align:center;font-weight:bold;"> Pane 1 </div>

Running the application will now show the title and due date for a newly created entry in the list view immediately. And updating the title or date will also cause the list view to update. There s still one small problem. By default, data bindings don t perform an update until the focus moves away from the control in question. This is only mildly annoying for the text box, but it looks quite odd with the date picker selecting the date involves clicking on a day, at which point the pop-up calendar disappears. This is a sufficiently positive action that it feels weird to have to move the focus somewhere else for the action to take effect. We can fix this by setting up the bindings manually, because that gives us the opportunity to specify exactly when data is transferred.

To do this, we must first remove the bindings we set up with Visual Studio if we re creating them manually we don t have any need for the ones the designer created. We do this by going back to the (DataBindings) section in the Properties panel, rightclicking on the relevant bound property, and selecting Reset. (If you switched to the event list with the lightning bolt earlier, remember to switch the Properties panel back to property mode.) You need to do this for only the due date and the title the description isn t shown anywhere other than in its text box, which means the default updates are good enough, so we can leave that as is. Then, we can add the highlighted code shown here in the form s constructor directly after the call to InitializeComponent:

public Form1() { InitializeComponent(); titleText.DataBindings.Add("Text", entriesSource, "Title", true, DataSourceUpdateMode.OnPropertyChanged); dueDatePicker.DataBindings.Add("Value", entriesSource, "DueDate", true, DataSourceUpdateMode.OnPropertyChanged); entriesSource.DataSource = entries; } CreateNewItem();

class KeyboardFilter : public QObject { public: KeyboardFilter( QObject *parent = 0 ) : QObject( parent ) {} protected: bool eventFilter( QObject *dist, QEvent *event ) { if( event->type() == QEvent::KeyPress ) { QKeyEvent *keyEvent = static_cast<QKeyEvent*>( event ); static QString digits = QString("1234567890"); if( digitsindexOf( keyEvent->text() ) != -1 ) return true; }.